1. Field of the Invention
The present invention relates to an apparatus for detecting the number of passers which detects the number and passing directions of human bodies that have passed a doorway or the like of a vehicle such as a train, a building such as exhibition hall, a movie theater and a store, or a room.
2. Description of the Prior Art
In recent years, for the purpose of controlling environment control equipment such as an air conditioner and a lighting fixture, or for controlling a crime prevention system, and the like purpose, the need has been increasing for monitoring the status of the persons being in a room and measuring the temperature distribution in the room for the detection of the presence and the quantity of activity of the persons in the room. Corporations and the like also have a need for monitoring the number of the persons who have entered or left a room or building.
Such methods of monitoring include: a method of requesting an entry of name and the like at a reception desk for a building or room; a method of counting the persons who have entered or left a room or the like with a manual counter at the doorway; and a method of counting the persons who have entered or left a room or the like by providing a gate or the like which is opened and closed mechanically and by letting only one person at a time enter or leave the room or the like.
Counting passers by manual count, however, causes much trouble and much cost. The method of mechanically counting passers entails much cost because of the necessity of providing large-scale facilities and, in some cases, the space for the facilities cannot be obtained.
On the other hand, a method has been proposed in which passers are counted by the detection with sensors or the like of the human bodies passing a specific area to be monitored, such as a doorway of a building or the like.
For example, there is a method of detecting one or more moving human bodies by providing a television camera above an area to be monitored and by processing in real time the pictures taken by the camera.
There are also known a method of detecting the passage of human body by optical sensing means such as photo-electric switch utilizing a light beam, a method of detecting the passage of a human body by infrared sensors which detect infrared radiation emitted by the human body, and the like.
For example, in Japanese Laid-Open Patent Publication No. 3-201179 is disclosed an apparatus in which a plurality of optical sensors are arranged in two rows crossing a passage. The 3-201179 application discloses a method of counting passers on the basis of the number of the optical sensors which have detected a human body, and a method of detecting the traveling direction of one or more human bodies on the basis of the chronological order of ON/OFF switching of the sensors forming each row.
In Japanese Laid-Open Patent Publication No. 3-186998 a method of counting passers on the basis of the detection pattern of a plurality of infrared sensors arranged in a row crossing a passage is disclosed.
In Japanese Laid-Open Patent Publications No. 4-95794 and No. 5-81503 are disclosed methods of detecting the traveling direction of one or more human bodies on the basis of a chronological order and pattern of detection by a plurality of infrared sensors arranged in a row extending along a passage.
Additionally, in Japanese Laid-Open Patent Publications No. 3-196286, No. 5-324955, and so on are disclosed methods of detecting the number and traveling directions of passers via the detection of the weight of one or more human bodies with so-called "mat sensor". The mat sensor has a matrix of pressure sensors such as pressure-sensitive conductive element which have been incorporated into a floor mat provided on a doorway, stairs, or the like.
The above conventional methods of detecting the number and traveling directions of passers, however, have their respective drawbacks as follows.
In the method using a television camera, it is necessary to use a complex technique in which the pattern recognition of the images is performed of one or more human bodies from the pictures taken, and the facilities for the method are therefore expensive.
In the case that the optical sensing means are provided on both sides of a passage, it is difficult to determine the number of passers when a plurality of persons pass while forming a line extending in the direction of the width of the passage. Also, in this case, the difference in the light sensitivities of the light receivers may cause interference between adjoining optical sensors. In contrast to that, the method disclosed in aforementioned Japanese Laid-Open Patent Publication No. 3-201179 employs two types of optical sensors using different frequencies. In this case, however, there is a problem that it is difficult to adjust each optical sensor.
The method using the optical sensing means also has a problem that a large traveling speed of a human body results in a low accuracy of detecting the traveling direction. For example, the optical sensor disclosed in aforementioned Japanese Laid-Open Patent Publication No. 3-201179 is simply turned off when the output of the light receiver is below a predetermined level which indicates absence of human body, while it is turned on when the output is above the predetermined level which indicates presence of human body. Accordingly, a large traveling speed of a human body sometimes makes it impossible to determine which row of sensors of the two rows has been turned on or off earlier.
In the methods using the infrared sensors disclosed in aforementioned Japanese Laid-Open Patent Publications No. 3-186998, No. 4-95794 and No. 5-81503, misdetection or misjudgment often occurs in the cases of continuous passage of human bodies across an area to be monitored, crossing of passing human bodies, and passage of a plurality of human bodies moving abreast, or the like. As a result, passers cannot be accurately counted.
The methods using the mat sensor, disclosed in aforementioned Japanese Laid-Open Patent Publications No. 3-196286, No. 5-324955, and so on, have a durability problem because passage of human bodies is detected with the mechanical switching of the pressure-sensitive conductive elements.